The Ruby Environment Variable API

Full talk and description available here:
http://confreaks.tv/videos/rubyconf2015-ruby-s-environment-variable-api

Transcript

2. Ruby’s Environment Variable API @JACKDANGER
3. Or: “require: cannot load such file” @JACKDANGER
4. The ideal world: $ > /bin/ruby /myonlyapp.rb
5. The ideal world: # myonlyapp.rb module Rails # … ten million lines of Ruby # copied and pasted from Rails source end module My class Application < Rails::Application # … way more stuff end end
7. Reality: $ > rvm list known # MRI Rubies [ruby-]1.8.6[-p420] [ruby-]1.8.7[-head] # security released on head [ruby-]1.9.1[-p431] [ruby-]1.9.2[-p330] [ruby-]1.9.3[-p551] [ruby-]2.0.0[-p647] [ruby-]2.1[.7] [ruby-]2.2[.3] [ruby-]2.2-head ruby-head
8. # MagLev maglev[-head] maglev-1.0.0 # Mac OS X Snow Leopard Or Newer macruby-0.10 macruby-0.11 macruby[-0.12] macruby-nightly macruby-head # IronRuby ironruby[-1.1.3] ironruby-head
9. $ > ~/.rubies/2.2.1/bin/ruby -r stuff ./app.rb # a real app.rb require 'thing' require 'other_thing' require 'nokogiri' # for some reason require 'custom-fork-of-sidekiq' require 'file-in-a-local-git-repo' require 'nokogiri/lib/specific_file'
10. $ > irb irb(main):001:0> require 'nokogiri' LoadError: cannot load such file -- nokogiri from /usr/ruby20/lib64/ruby/2.0.0/rubygems/core_ext kernel_require.rb:55:in `require' from /usr/ruby20/lib64/ruby/2.0.0/rubygems/core_ext kernel_require.rb:55:in `require' from (irb):1 from /usr/ruby20/bin/irb:16:in `<main>'
12. RVM rbenv chruby Bundler Rubygems Ruby itself Pretend there are logos!
13. How highly-paid engineers solve problems with Ruby dependencies: 1. $ > rake 2. $ > bundle exec rake 3. $ > rvm use some-ruby && bundle exec rake 4. Close your terminal and open it again 5. Ask a coworker 6. $ > rvm implode && (curl https://get.rvm.io | bash) 7. re-run the setup script that your team uses 8. reboot your machine 9. buy a new macbook 10. become a farmer
14. Title Footnote
15. Becoming a superhero PARTS 1 - 13: learn the tools.
16. ENV Variables: A global hash of strings that your program inherits from it’s parent program (i.e. your shell session).
17. $ > env
18. $ > env | grep HOME
19. $ > ohdear=uhoh $ > env | grep ohdear Where did it go?
20. Where did it go? $ > echo $ohdear uhoh $ > ohdear=uhoh $ > env | grep ohdear
21. $ > ohdear=uhoh && env | grep ohdear $ > echo $ohdear uhoh $ > ohdear=uhoh $ > export ohdear=uhoh $ > env | grep ohdear
22. Your OS (pid 1) $ export happy=yes $ food=pizza
23. Your OS (pid 1) Your shell $ export happy=yes $ food=pizza export happy=yes ohdear=uhoh export happy=yes `env`
24. Your OS (pid 1) Your shell $ export happy=yes $ food=pizza export happy=yes export ohdear=uhoh export happy=yes export ohdear=uhoh `env`
25. $ > env | grep PATH $ > echo $PATH $PATH
26. $ > echo $PATH | tr : "\n" /usr/lib64/qt-3.3/bin /usr/pgsql-9.1/bin /usr/local/go/bin /usr/local/bin /bin /usr/bin /usr/local/sbin /usr/sbin /sbin $PATH
27. $ > echo $PATH | tr : "\n" /usr/lib64/qt-3.3/bin /usr/pgsql-9.1/bin /usr/local/go/bin /usr/local/bin /bin /usr/bin /usr/local/sbin $PATH
28. $ > strace sh -c 'missingcommand' execve("/bin/sh", ["sh", "-c", "missingcommand"], [/* 37 vars */]) = 0 stat("/usr/lib64/qt-3.3/bin/missingcommand") = -1 ENOENT stat("/usr/pgsql-9.1/bin/missingcommand") = -1 ENOENT stat("/usr/local/go/bin/missingcommand") = -1 ENOENT stat("/usr/local/bin/missingcommand") = -1 ENOENT stat("/bin/missingcommand") = -1 ENOENT stat("/usr/bin/missingcommand") = -1 ENOENT stat("/usr/local/sbin/missingcommand") = -1 ENOENT stat("/usr/sbin/missingcommand") = -1 ENOENT stat("/sbin/missingcommand") = -1 ENOENT write(2, "sh: missingcommand: command not "..., 38) = 38 (ENOENT = "No such file or directory”) $PATH
29. $ > strace sh -c 'missingcommand' execve("/bin/sh", ["sh", "-c", "missingcommand"], [ stat("/usr/lib64/qt-3.3/bin/missingcommand") = -1 E stat("/usr/pgsql-9.1/bin/missingcommand") = -1 ENOE stat("/usr/local/go/bin/missingcommand") = -1 ENOEN stat("/usr/local/bin/missingcommand") = -1 ENOENT stat("/bin/missingcommand") = -1 ENOENT stat("/usr/bin/missingcommand") = -1 ENOENT stat("/usr/local/sbin/missingcommand") = -1 ENOENT stat("/usr/sbin/missingcommand") = -1 ENOENT stat("/sbin/missingcommand") = -1 ENOENT write(2, "sh: missingcommand: command not "..., 38) $ > echo $PATH | tr : "\n" /usr/lib64/qt-3.3/bin /usr/pgsql-9.1/bin /usr/local/go/bin /usr/local/bin /bin /usr/bin /usr/local/sbin /usr/sbin /sbin $PATH
30. $ > strace sh -c 'missingcommand' execve("/bin/sh", ["sh", "-c", "missingcommand"], [ stat("/usr/lib64/qt-3.3/bin/missingcommand") = -1 E stat("/usr/pgsql-9.1/bin/missingcommand") = -1 ENOE stat("/usr/local/go/bin/missingcommand") = -1 ENOEN stat("/usr/local/bin/missingcommand") = -1 ENOENT stat("/bin/missingcommand") = -1 ENOENT stat("/usr/bin/missingcommand") = -1 ENOENT stat("/usr/local/sbin/missingcommand") = -1 ENOENT stat("/usr/sbin/missingcommand") = -1 ENOENT stat("/sbin/missingcommand") = -1 ENOENT write(2, "sh: missingcommand: command not "..., 38) $ > echo $PATH | tr : “\n” /usr/lib64/qt-3.3/bin /usr/pgsql-9.1/bin /usr/local/go/bin /usr/local/bin /bin /usr/bin /usr/local/sbin /usr/sbin /sbin $PATH
31. $ > strace sh -c 'missingcommand' execve("/bin/sh", ["sh", "-c", "missingcommand"], [ stat("/usr/lib64/qt-3.3/bin/missingcommand") = -1 E stat("/usr/pgsql-9.1/bin/missingcommand") = -1 ENOE stat("/usr/local/go/bin/missingcommand") = -1 ENOEN stat("/usr/local/bin/missingcommand") = -1 ENOENT stat("/bin/missingcommand") = -1 ENOENT stat("/usr/bin/missingcommand") = -1 ENOENT stat("/usr/local/sbin/missingcommand") = -1 ENOENT stat("/usr/sbin/missingcommand") = -1 ENOENT stat("/sbin/missingcommand") = -1 ENOENT write(2, "sh: missingcommand: command not "..., 38) $ > echo $PATH | tr : “\n” /usr/lib64/qt-3.3/bin /usr/pgsql-9.1/bin /usr/local/go/bin /usr/local/bin /bin /usr/bin /usr/local/sbin /usr/sbin /sbin $PATH
32. $ > strace sh -c 'missingcommand' execve("/bin/sh", ["sh", "-c", "missingcommand"], [ stat("/usr/lib64/qt-3.3/bin/missingcommand") = -1 E stat("/usr/pgsql-9.1/bin/missingcommand") = -1 ENOE stat("/usr/local/go/bin/missingcommand") = -1 ENOEN stat("/usr/local/bin/missingcommand") = -1 ENOENT stat("/bin/missingcommand") = -1 ENOENT stat("/usr/bin/missingcommand") = -1 ENOENT stat("/usr/local/sbin/missingcommand") = -1 ENOENT stat("/usr/sbin/missingcommand") = -1 ENOENT stat("/sbin/missingcommand") = -1 ENOENT write(2, "sh: missingcommand: command not "..., 38) $ > echo $PATH | tr : “\n” /usr/lib64/qt-3.3/bin /usr/pgsql-9.1/bin /usr/local/go/bin /usr/local/bin /bin /usr/bin /usr/local/sbin /usr/sbin /sbin $PATH
33. $ > strace sh -c 'missingcommand' execve("/bin/sh", ["sh", "-c", "missingcommand"], [ stat("/usr/lib64/qt-3.3/bin/missingcommand") = -1 E stat("/usr/pgsql-9.1/bin/missingcommand") = -1 ENOE stat("/usr/local/go/bin/missingcommand") = -1 ENOEN stat("/usr/local/bin/missingcommand") = -1 ENOENT stat("/bin/missingcommand") = -1 ENOENT stat("/usr/bin/missingcommand") = -1 ENOENT stat("/usr/local/sbin/missingcommand") = -1 ENOENT stat("/usr/sbin/missingcommand") = -1 ENOENT stat("/sbin/missingcommand") = -1 ENOENT write(2, "sh: missingcommand: command not "..., 38) $ > echo $PATH | tr : “\n” /usr/lib64/qt-3.3/bin /usr/pgsql-9.1/bin /usr/local/go/bin /usr/local/bin /bin /usr/bin /usr/local/sbin /usr/sbin /sbin $PATH
34. $ > echo $GEM_PATH | tr : "\n" /Users/jackdanger/.gem/ruby/2.2.2 /Users/jackdanger/.rubies/ruby-2.2.2/lib/ruby/gems/2.2.0 $ > ruby -e 'p Gem.default_path.split(":")' /Users/jackdanger/.gem/ruby/2.2.2 /Users/jackdanger/.rubies/ruby-2.2.2/lib/ruby/gems/2.2.0 $GEM_PATH
35. $ > echo $GEM_PATH | tr : "\n" /Users/jackdanger/.gem/ruby/2.2.2 /Users/jackdanger/.rubies/ruby-2.2.2/lib/ruby/gems/2.2.0 $ > export GEM_HOME=/tmp/lolwut $ > export GEM_PATH=/tmp/lolwut:$GEM_PATH $ > gem install eallydumb $ > gem list # now includes ‘eallydumb’ $ > ls /tmp/lolwut # behold it is there $GEM_PATH
36. $ > echo $GEM_PATH | tr : "\n" /Users/jackdanger/.gem/ruby/2.2.2 /Users/jackdanger/.rubies/ruby-2.2.2/lib/ruby/gems/2.2.0 $ > export GEM_HOME=/tmp/lolwut $ > export GEM_PATH=/tmp/lolwut:$GEM_PATH $ > gem install eallydumb $ > gem list # now includes ‘eallydumb’ $ > ls /tmp/lolwut # behold it is there $GEM_PATH
37. $GEM_PATH $PATH Colon-separated list of directories in which to find an executable Where `gem install` puts stuff $GEM_HOME $GEM_PATH Colon-separated list of directories in which to find a gem
38. One more path: $ > ruby -e 'p $LOAD_PATH' (Not an environment variable!)
39. $ > ruby -r pp -e 'pp $LOAD_PATH' ["/usr/lib/ruby/site_ruby/1.8", "/usr/lib64/ruby/site_ruby/1.8", "/usr/lib/ruby/site_ruby", "/usr/lib64/ruby/site_ruby", "/usr/lib64/site_ruby/1.8", "/usr/lib64/site_ruby/1.8/x86_64-linux", "/usr/lib64/site_ruby", "/usr/lib/ruby/1.8", "/usr/lib64/ruby/1.8", "/usr/lib64/ruby/1.8/x86_64-linux"]] $LOAD_PATH
40. $ > strace ruby -e 'require "missingfile"' execve("/usr/bin/ruby", ["ruby", "-e", "require \"missingfile\""], [/* 38 vars */]) = 0 stat("/usr/lib/ruby/site_ruby/1.8/missingfile.rb") = -1 ENOENT stat("/usr/lib/ruby/site_ruby/1.8/missingfile.so") = -1 ENOENT stat("/usr/lib64/ruby/site_ruby/1.8/missingfile.rb") = -1 ENOENT stat("/usr/lib64/ruby/site_ruby/1.8/missingfile.so") = -1 ENOENT stat("/usr/lib/ruby/site_ruby/missingfile.rb") = -1 ENOENT stat("/usr/lib/ruby/site_ruby/missingfile.so") = -1 ENOENT stat("/usr/lib64/ruby/site_ruby/missingfile.rb") = -1 ENOENT stat("/usr/lib64/ruby/site_ruby/missingfile.so") = -1 ENOENT stat("/usr/lib64/site_ruby/1.8/missingfile.rb") = -1 ENOENT stat("/usr/lib64/site_ruby/1.8/missingfile.so") = -1 ENOENT stat("/usr/lib64/site_ruby/missingfile.rb", 0x7ffffeeca290) = -1 ENOENT stat("/usr/lib64/site_ruby/missingfile.so", 0x7ffffeeca290) = -1 ENOENT stat("/usr/lib/ruby/1.8/missingfile.rb", 0x7ffffeeca290) = -1 ENOENT $LOAD_PATH
41. $LOAD_PATH $ > ruby -r pp -e 'pp $LOAD_PATH' [“/usr/lib/ruby/site_ruby/1.8", "/usr/lib64/ruby/site_ruby/1.8", "/usr/lib/ruby/site_ruby", "/usr/lib64/ruby/site_ruby", "/usr/lib64/site_ruby/1.8", "/usr/lib64/site_ruby", "/usr/lib/ruby/1.8", "/usr/lib64/ruby/1.8"]] $ > strace ruby -e 'require "missingfile"' execve("/usr/bin/ruby", ["ruby", "-e", "require \"mis stat("/usr/lib/ruby/site_ruby/1.8/missingfile.rb") = stat("/usr/lib/ruby/site_ruby/1.8/missingfile.so") = stat("/usr/lib64/ruby/site_ruby/1.8/missingfile.rb") stat("/usr/lib64/ruby/site_ruby/1.8/missingfile.so") stat("/usr/lib/ruby/site_ruby/missingfile.rb") = -1 E stat("/usr/lib/ruby/site_ruby/missingfile.so") = -1 E stat("/usr/lib64/ruby/site_ruby/missingfile.rb") = -1 stat("/usr/lib64/ruby/site_ruby/missingfile.so") = -1 stat("/usr/lib64/site_ruby/1.8/missingfile.rb") = -1 stat("/usr/lib64/site_ruby/1.8/missingfile.so") = -1 stat("/usr/lib64/site_ruby/missingfile.rb", 0x7ffffee stat("/usr/lib64/site_ruby/missingfile.so", 0x7ffffee stat("/usr/lib/ruby/1.8/missingfile.rb", 0x7ffffeeca2 stat("/usr/lib/ruby/1.8/missingfile.so", 0x7ffffeeca2 stat("/usr/lib64/ruby/1.8/missingfile.rb", 0x7ffffeec stat("/usr/lib64/ruby/1.8/missingfile.so", 0x7ffffeec
42. $LOAD_PATH $ > ruby -r pp -e 'pp $LOAD_PATH' [“/usr/lib/ruby/site_ruby/1.8", "/usr/lib64/ruby/site_ruby/1.8", "/usr/lib/ruby/site_ruby", "/usr/lib64/ruby/site_ruby", "/usr/lib64/site_ruby/1.8", "/usr/lib64/site_ruby", "/usr/lib/ruby/1.8", "/usr/lib64/ruby/1.8"]] $ > strace ruby -e 'require "missingfile"' execve("/usr/bin/ruby", ["ruby", "-e", "require \"mis stat("/usr/lib/ruby/site_ruby/1.8/missingfile.rb") = stat("/usr/lib/ruby/site_ruby/1.8/missingfile.so") = stat("/usr/lib64/ruby/site_ruby/1.8/missingfile.rb") stat("/usr/lib64/ruby/site_ruby/1.8/missingfile.so") stat("/usr/lib/ruby/site_ruby/missingfile.rb") = -1 E stat("/usr/lib/ruby/site_ruby/missingfile.so") = -1 E stat("/usr/lib64/ruby/site_ruby/missingfile.rb") = -1 stat("/usr/lib64/ruby/site_ruby/missingfile.so") = -1 stat("/usr/lib64/site_ruby/1.8/missingfile.rb") = -1 stat("/usr/lib64/site_ruby/1.8/missingfile.so") = -1 stat("/usr/lib64/site_ruby/missingfile.rb", 0x7ffffee stat("/usr/lib64/site_ruby/missingfile.so", 0x7ffffee stat("/usr/lib/ruby/1.8/missingfile.rb", 0x7ffffeeca2 stat("/usr/lib/ruby/1.8/missingfile.so", 0x7ffffeeca2 stat("/usr/lib64/ruby/1.8/missingfile.rb", 0x7ffffeec stat("/usr/lib64/ruby/1.8/missingfile.so", 0x7ffffeec /usr/lib/ruby/site_ruby/1.8 /usr/lib/ruby/site_ruby/1.8/missingfile.rb
43. $LOAD_PATH $ > ruby -r pp -e 'pp $LOAD_PATH' [“/usr/lib/ruby/site_ruby/1.8", "/usr/lib64/ruby/site_ruby/1.8", "/usr/lib/ruby/site_ruby", "/usr/lib64/ruby/site_ruby", "/usr/lib64/site_ruby/1.8", "/usr/lib64/site_ruby", "/usr/lib/ruby/1.8", "/usr/lib64/ruby/1.8"]] $ > strace ruby -e 'require "missingfile"' execve("/usr/bin/ruby", ["ruby", "-e", "require \"mis stat("/usr/lib/ruby/site_ruby/1.8/missingfile.rb") = stat("/usr/lib/ruby/site_ruby/1.8/missingfile.so") = stat("/usr/lib64/ruby/site_ruby/1.8/missingfile.rb") stat("/usr/lib64/ruby/site_ruby/1.8/missingfile.so") stat("/usr/lib/ruby/site_ruby/missingfile.rb") = -1 E stat("/usr/lib/ruby/site_ruby/missingfile.so") = -1 E stat("/usr/lib64/ruby/site_ruby/missingfile.rb") = -1 stat("/usr/lib64/ruby/site_ruby/missingfile.so") = -1 stat("/usr/lib64/site_ruby/1.8/missingfile.rb") = -1 stat("/usr/lib64/site_ruby/1.8/missingfile.so") = -1 stat("/usr/lib64/site_ruby/missingfile.rb", 0x7ffffee stat("/usr/lib64/site_ruby/missingfile.so", 0x7ffffee stat("/usr/lib/ruby/1.8/missingfile.rb", 0x7ffffeeca2 stat("/usr/lib/ruby/1.8/missingfile.so", 0x7ffffeeca2 stat("/usr/lib64/ruby/1.8/missingfile.rb", 0x7ffffeec stat("/usr/lib64/ruby/1.8/missingfile.so", 0x7ffffeec /usr/lib/ruby/site_ruby/1.8 /usr/lib/ruby/site_ruby/1.8/missingfile.rb
44. $LOAD_PATH $ > echo 'puts :hi' > myfile.rb
45. $LOAD_PATH $ > echo 'puts :hi' > myfile.rb $ > ruby -e 'require "myfile"' /usr/ruby/lib64/ruby/2.0.0/rubygems/core_ext/ kernel_require.rb:55:in `require': cannot load such file -- myfile (LoadError) from /usr/ruby/lib64/ruby/2.0.0/rubygems/core_ext/ kernel_require.rb:55:in `require' from -e:1:in `<main>'
46. $LOAD_PATH $ > echo 'puts :hi' > myfile.rb $ > ruby -e '$LOAD_PATH << "."; require "myfile"' hi
47. $LOAD_PATH $ > echo 'puts :hi' > myfile.rb $ > ruby -I . -e 'require "myfile"' hi
48. How Bundler works irb:0> $LOAD_PATH << "~/.gems/2.2.0/active_record-4.1.0/lib/" irb:1> $LOAD_PATH << "~/.gems/2.2.0/actionpack-4.1.0/lib/" irb:2> $LOAD_PATH << "~/.gems/2.2.0/rake-2.3.4/lib" $ > export RUBYOPT="-rbundler/setup"
49. ENV vars Flags $ > export RUBYLIB=. $ > ruby -I . (ruby -e “$LOAD_PATH << ‘.’”)
50. ENV vars $ > export RUBYLIB=. Flags $ > ruby -I . $ > export RUBYOPT=“-r rails” $ > ruby -r rails (ruby -e “$LOAD_PATH << ‘.’”)
51. ENV vars $ > export RUBYLIB=. Flags $ > ruby -I . $ > export RUBYOPT=“-r rails” $ > ruby -r rails (ruby -e “$LOAD_PATH << ‘.’”) $ > export RUBYOPT="-I /fakedir -I . -r rails” $ > ruby -e ‘p Rails’ Rails
53. • Rubygems • Rip • RVM • Bundler • rbenv • chruby 2003 (!!) 2009 2009 2009 2011 2012
55. What Ruby cares about $LOAD_PATH Array of directories in which to find a file that’s been require()’d Flags to pass to ruby every time it’s run $RUBYOPT $RUBYLIB A colon-separated list of directories to add to the $LOAD_PATH
56. What RVM* Cares about $PATH Array of directories in which to find an executable ‘ruby’, ‘rake’, etc. $GEM_PATH Colon-separated list of directories in which to find a gem Where to install gems $GEM_HOME * and rbenv, chruby, …
57. What Rubygems cares about $GEM_PATH Colon-separated list of directories in which to find a gem Where to install gems $GEM_HOME
58. What Bundler cares about Loads of configs you can override $BUNDLE_*
61. How it all connects Ruby
62. Ruby Rubygems alias gem_original_require require
64. Ruby Rubygems alias gem_original_require require
65. Ruby Rubygems Bundler reverse_rubygems_kernel_mixin()
67. Ruby Rubygems Bundler reverse_rubygems_kernel_mixin()
68. Ruby Bundler Rubygems Can read Gemfile.lock without Bundler Is checked into Ruby core
69. What I recommend: Go through the exercises in these slides yourself Try replacing RVM and rbenv with chruby https://github.com/postmodern/chruby
70. Q&A
71. square.com